MAYBE Diego Costa deliberately threw his chest in the way of David Luiz's elbow. Perhaps he maliciously blocked Edinson Cavani's kick with his ankle.

Because if not, despite the warnings of Paris Saint-Germain manager Laurent Blanc, the only thing the Chelsea striker provoked last night were a few thoughts.

Key among those has to be that, while he is undoubtedly no angel, perhaps there are times when, as Jose Mourinho always contests, he is a man more sinned against than sinning.

Mourinho has known Costa since he was a fresh-faced teenager newly-arrived in Portugal. It was why he was so delighted to speak of his newest acquisition in the summer in almost avuncular terms.

It was almost as if Mourinho had finally found his kindred spirit, a special one on the pitch - same feistiness, same win-at-all-costs mentality, same propensity to bend the rules. If Costa could arrive unnoticed at the far post in a kit bin, he would.

Instead, he has to resort to more subtle ploys - earning himself the honour of being singled out by Blanc in the pre-match press conference as some sort of "agent provocateur".

He likes contact, and provokes opposition players

Laurent Blanc

"He likes contact, and provokes opposition players," he said. "He thrives off that. The most important thing is to not get caught up in the way he plays." Yet four minutes into the game PSG were already playing to his level, Javier Pastore treating him to a subtle dig in the ribs which left the Chelsea striker writhing on the ground.

His running battle with David Luiz did not start until the 12th minute. The Brazil international bundled somewhat unnecessarily into the back of Costa, appeared to retrieve something from the ground that had been dislodged in the collision, then inexplicably collapsed to the turf himself clutching his chest.

Costa shrugged his innocence, but referee Bjorn Kuipers could only guess if it was genuine or not, and one sensed that this was PSG's attempt not so much at psychological warfare as character assassination.

Certainly no amount of television replays will ever reveal what all the subsequent finger-wagging from Luiz was genuinely all about.

The Chelsea player rode it all serenely, though. and was just a bemused bystander as his opposite number, Zlatan Ibrahimovic, dived straight into trouble at the other end of the field.

But the action was not far from Costa and Luiz for long and perhaps the latter could have followed his team-mate down the tunnel when the pair next, for want of a better word, clashed.

Four minutes before the two of them were running towards the PSG goal. Luiz's elbow came out and, although it is unclear how much contact there was, this time it was Costa in a crumpled heap on the floor.

Again there was no action from the officials - maybe the Dutch referee thought the striker simply liked throwing himself to the floor.

Certainly, that is the only thing that would explain why Costa did not earn Chelsea a penalty when Edinson Cavani succeeed where five of his PSG team-mates failed by tripping him in the box.

But really, this was the Luiz and Costa show.

Costa was rightly yellow carded for an anything-but-subtle challenge on Thiago Silva and of course, Luiz had to run across, face up to his tormentor and, in keeping with his general behaviour, instantly simulate that he had been head-butted.

As a result, Luiz followed him into the book. It seemed the former Chelsea man wanted to follow him everywhere.

When Costa teed up Gary Cahill for a Chelsea goal, Luiz took it upon himself to score at the other end and level things up again. Yes, Costa really should not have pushed over Thiago Motta in injury time, risking a second yellow card. But really it was about Costa v Luiz.

As for the final word? Well, such is the nature of sport – good sport and bad sport – that at the end of the night only one of them was going to make it into the next round.